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How to deal with Car Air-conditioning Problems

How to deal with Car Air-conditioning Problems

How to deal with Car..

  • 03 Aug 2016, 76120 Views

Roshun

Super Moderator

Member: 13 Oct, 2015

Total Posts: 2035

  • 3 Aug 2016, 7:09 pm ( 1 Photo )
The car air-conditioner is probably one of the biggest comfort features your car can have. When it conks off on a hot summer’s day, your car can get very, very uncomfortable, really quickly. As cars age, the air-conditioning system will also need routine maintenance. In this thread, we deal with common car AC problems and how to fix them – sometimes, it usually is a very minor issue that can lead to major discomfort.
Before we get into the issues with car air-conditioning, let me just lay bare the basic layout of a car air-conditioning system, so that it would be easier for you to identify problem areas and get it fixed. Share your car AC experiences in this thread as well.
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How does the car AC work?
The car AC works exactly like a household air-conditioner or a refrigerator. It works on the principle of heat-exchange. For this to happen, it uses a refrigerant (presently R134-a, earlier R12) that transforms from liquid to gas and back to liquid, and in the process it absorbs or releases heat. When it expands (from liquid to gas form), it absorbs heat.
The AC compressor, compresses low-pressure gas into high-pressure gas, heating it up in the process because of the compression. The condenser and condenser fan help in cooling this gas down, turning it into a high-pressure liquid form, losing some of the heat in the process. This liquid, high-pressure refrigerant flows through an expansion valve just before it enters the cabin, allowing it to expand, reducing pressure and further cooling it down. This cold liquid flows through the internal condenser (or cooling coil as it is commonly called), where it absorbs heat from the cabin as it evaporates into gaseous form. A blower motor helps with this process and in turn pushes that cold air into the cabin. The low-pressure gaseous refrigerant travels back to the compressor, where it is compressed into a high-pressure gas and the cycle repeats.
What are the common issues with car AC systems failing?
Let’s take a look at some of the most common problems that car ACs face and how to diagnose them. (Next Post)

Roshun

Super Moderator

Member: 13 Oct, 2015

Total Posts: 2035

  • 3 Aug 2016, 7:11 pm
There is little or no AC gas in the system. What to do?
How do you check if there is no gas in the system? Well, if everything else is running in the car – the blower motor is working fine, warm air is coming out of the AC vents, the AC compressor clicks on, the condenser fan / engine fan is whirring away, but yet the car is not cooling down, it could be a problem with low AC gas.
A characteristic, tell-tale sign of gas being low is if you get a hissing sound as soon as you turn on the AC, which refuses to die down and no cool air or very mild cool air comes through the vents. Now, car ACs don’t just leak gas on their own. A well-maintained system can run for years with just a minor check and top-up of refrigerant every 2-3 years. If the gas has escaped from the system, in all probability there is a leak somewhere.
Don’t just get the gas refilled at an AC service centre before conducting a complete check on the system to figure out why it has leaked out. You will need to check the joints of the pipes and hoses that come from the condenser (especially the high-pressure lines, as they are usually the culprits). Sometimes a leak is not visible to the naked eye and would require a UV dye to be fed into the system (through the low-pressure valve) and checked with a UV light for leakage. The desi way of doing it though is simple soapy water, poured over the pipe and valves to check for leaks.
Another problem area is the pressure switch – this is a fail-safe device that will blow if the refrigerant pressure gets too high, to prevent damage to other components. It is also the device that regulates the condenser fan(s). Check for leaks on this switch.
The condenser itself is prone to damage from stones and other flying debris from the road and is usually one of the first things to get damaged in a front-end collision. Check the condition of the condenser, while checking for gas leaks. The evaporator / condenser inside the cabin is usually not one that fails easily, but it can get clogged with dirt, which leads to a different problem with the AC – that of low air flow, bad smell and poor cooling over longer durations.

Roshun

Super Moderator

Member: 13 Oct, 2015

Total Posts: 2035

  • 3 Aug 2016, 7:51 pm ( 1 Photo )
I turn on the AC, but the compressor does not come on. What could be the problem?

How do you check if the AC compressor is not coming on? Open the bonnet of the car, locate the AC compressor and then start the car, without turning on the AC. You will observe that the belt that turns the AC compressor pulley, will continue to rotate and the outer part of the pulley will turn with it, but the centre part of it will not turn. This part is the electro-magnetic clutch that operates the AC compressor and cycles it on and off. Now turn on the AC switch. The centre part of the compressor will also begin to turn and the AC will power on. (See image below)
Now, there is a fail-safe built into the AC compressor. If there is too little refrigerant in the system the compressor will not come on. This is dictated by the pressure switch that will sense the pressure in the system. Similarly, if the pressure is too high it won’t let the compressor cut in. Check the gas level and pressure in the system first.
Then check for an electrical fault – a fuse or relay that powers the compressor could have blown or gone bad. This could be due to a short circuit caused by water or a wiring fault. Determine why the fuse has blown first.
The last resort is if the compressor itself has gone bad. This will usually have other symptoms as well, such as oil leaking out of it, abnormal squeaking, rattling noises coming out of it and sometimes, even a wobbly pulley, indicative of a bad or broken bearing. Replacing a compressor is usually an expensive affair. At times, it is only the electromagnetic clutch that has gone bad, and that can be repaired. Still, the longevity of the compressor will be suspect. To ensure your AC compressor has a long life, make sure that every 2-3 years, when you check the AC system, along with the refrigerant gas, a few ml of compressor oil is added to the system to keep it lubricated.
Cutaway of an AC compressor: (This is a reciprocating compressor, some cars also use a scroll type compressor)
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Kavinraj_Karupa..

First Gear

Member: 16 Jun, 2016

Total Posts: 31

  • 12 Aug 2016, 2:03 am
This was really useful. I actually have faced a situation, where while I was driving, gradually we experienced that the cool air is not coming out of the AC Vents but only blower is running. I was not sure of what might be the mistake. So simply what I did was to turn off the AC leaving only the blower ON for some 10 minutes. Then turned the AC ON and it was working. So when I went on a trip with my family, I had to follow this, repeated some 4 times in two days. What could be the issue?

Roshun

Super Moderator

Member: 13 Oct, 2015

Total Posts: 2035

  • 12 Aug 2016, 12:13 pm
"Originally posted by Kavinraj_Karupanna_Gounder_Subramanian"
This was really useful. I actually have faced a situation, where while I was driving, gradually we experienced that the cool air is not coming out of the AC Vents but only blower is running. I was not sure of what might be the mistake. So simply what I did was to turn off the AC leaving only the blower ON for some 10 minutes. Then turned the AC ON and it was working. So when I went on a trip with my family, I had to follow this, repeated some 4 times in two days. What could be the issue?
This issue happens when ice forms on your condenser coil behind the dashboard, if the AC gets too cold. When that happens, then the cooling effect drops as heat exchange does not take place properly because ice has formed on the condenser. If you turn off the compressor and let only the fan run for a while, the air flow will gradually melt the ice (you will see water dripping under the car) and once all the ice has melted, cooling will be restored once you turn on the compressor. It usually happens on long trips, if the AC has been on for a while. Ford and Mahindra vehicles are notorious for this as they have really powerful air-conditioners. It happens with others as well, if the AC is really good. To avoid this, don't set the temperature too cold. On long trips, every now and then, switch off the AC compressor for a few minutes to de-ice the condenser.

JOY MRC

Moderator

Member: 05 Jan, 2016

Total Posts: 606

  • 12 Aug 2016, 1:40 pm ( 3 Photos )
Kavinraj_Karupanna_Gounder_Subramanian Like Roshun mentioned your car's air conditioning is very effective and it is indeed the Evaporator getting Ice'd Up.You must be running it in the coldest position(100% in the Blue region/16 degrees) and hence the compressor is working in full swing without cutting off I presume.This is how I run my car too as in City runs,after parking under sun it sure helps to chill the cabin in minutes.But the downside can be felt only on the long trips.After an hour or so,even if we set the fan speed to 1,the cabin gets too cold to be comfortable that we have to point the vents to some other direction,then that place get misted and eventually...

In older cars when this kind of an issue turns up,the first thing to check would be the resistor kind of Thermo-switch which can be adjusted/set to when the compressor would kick in and turn off(was a 50-75 rupee spare part) but all these are sensed by Electronic Modules and controlled by ECU these days(BIG Money,Yes ).
So,The Right way to do it is to set the Temp. knob or Thermostat to the desired level after cabin is chilled to the comfort levels.

If this Icing issue occurs again after following this procedure,then you need to check the Evaporator coil drain tube to see if its clogged and also a clean up of the Evaporator Coil.If Water/Moisture is not leaving the system as it should,the low temp will immediately turn the moisture to ice causing the same issue.Keep us Posted.Regards...

maha2804

First Gear

Member: 18 Aug, 2016

Total Posts: 1

  • 18 Aug 2016, 2:15 am
Nice post. I have a swift. And frequently when the ac is turned on ad running, ticking noise is heard. No mechanic could solve the issue. I hv this issue for 3 years now. The pressure is fine, there is no cooling issue. When we switch off and switch on the noise stops. What is the root cause of this sound?

venkatesh_raman..

First Gear

Member: 08 Jul, 2017

Total Posts: 1

  • 8 Jul 2017, 6:04 pm
Hi
I have Ford figo diesel. Have a strange problem.. On highway drive ac works fine for about 2hrs. Then suddenly air blower unable to push air through.. The next day ac works fine again.. This is second time this is happening in long drive. Any suggestions.Roshun

Arjun

Moderator

Member: 26 Oct, 2015

Total Posts: 807

  • 10 Jul 2017, 11:35 am
Venkatesh_ramanathan
This is a common problem with the Figo. The reason is freezing on the condenser. I also own a Figo and have noticed this a couple of times during long drives. It happens more during rains. The condenser intake freezes up and this blocks the air flow.
The problem goes away if you switch off use the AC for like 15-20 minutes.You can leave the blower on. I usually take a break during these duration and the AC works fine after that.

Abhishek_Sarasw..

First Gear

Member: 21 Nov, 2017

Total Posts: 1

  • 21 Nov 2017, 12:21 am
Arjun
Facing this AC problem in my 5 Yrs old Figo and tried many things but issue remains same. Surprisingly none of service Center have given accurate reason and solution till date. Have topped refrigerant, Changed thermistor but all in vain. Will switch off and on AC as recommended by you in next trip. However Figo should have a permanent solution for this. Any other suggestion?

John_sparks

First Gear

Member: 25 Nov, 2017

Total Posts: 1

  • 25 Nov 2017, 8:56 pm
Abhishek_Saraswat
Roshun
Roshun
Hi
Very helpful post. I am facing some issues on my ac, Now it got fixed.
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